Frit sealing system and method of manufacturing organic light-emitting display (OLED) apparatus using the same

ABSTRACT

A frit sealing system and a method of manufacturing an organic light-emitting display (OLED) using the frit sealing system are disclosed. In one embodiment, the frit sealing system includes: a thermal expansion film formed on the second substrate to pressurize the second substrate when heat is applied to the frit and thermal expansion film, wherein the frit is interposed between the first and second substrates and a mask formed on the thermal expansion film.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the benefit of Korean Patent Application No.10-2009-0122534, filed on Dec. 10, 2009, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The disclosed technology relates to a frit sealing system and a methodof manufacturing an organic light-emitting display (OLED) using thesame.

2. Description of the Related Technology

Many modern displays use thin film technology to make a type flat paneldisplay (FPD). Among FPDS, an electroluminescent display apparatus isself-emissive, and has a wide viewing angle, a high-quality contrast,and a fast response time. Thus, the electroluminescent display hasattracted attention as a next generation display. Also, an organiclight-emitting display (OLED), including organic light-emitting layers,has enhanced luminance, driving voltage, and response time. The OLEDapparatus has also a polychromatic characteristic in comparison with aninorganic light-emitting display (ILED).

SUMMARY OF CERTAIN INVENTIVE ASPECTS

One aspect of the present invention is a frit sealing system forimproving an adhesive strength of a frit and a method of manufacturingan organic light-emitting display (OLED) using the frit sealing system.

Another aspect is a frit sealing system which includes a thermalexpansion film expanding when a laser is radiated on a frit topressurize first and second substrates and bond the first and secondsubstrates to each other, in order to improve an adhesive strength ofthe frit and a method of manufacturing an OLED using the same.

Another aspect is a frit sealing system for bonding first and secondsubstrates to each other using a frit, including: a laser radiator whichradiates a laser on the frit coated between the first and secondsubstrates; a thermal expansion film which is formed on the secondsubstrate to pressurize the second substrate when the laser radiatorradiates the laser on the frit; and a mask which is disposed on thethermal expansion film.

An area of the thermal expansion film on which the laser is radiated mayexpand locally.

The thermal expansion film may be patterned such that the thermalexpansion film is not formed in an area on which the frit is coated.

The mask may include a base which is formed of a transparent materialand a metal layer which is formed on a surface of the base.

The metal layer may be patterned to correspond to a movement path of thelaser radiator.

A portion of the laser radiated toward the second substrate may melt thefrit, and an other portion of the laser may expand an area of thethermal expansion film around the frit.

The other portion of the laser may heat the metal layer of the mask, andthe heated metal layer may expand the thermal expansion film.

The thermal expansion film may include polymer or elastomer having arelatively high thermal expansion coefficient.

The frit sealing system may further include a pressurizer whichpressurizes the mask in order to keep a fixed position of the mask whenthe thermal expansion film expands.

The laser radiator may move along a trajectory corresponding to a closedcurve to radiate the laser on the frit which is disposed on a surface ofthe first substrate in the closed curve, in order to heat the frit andexpand an area of the thermal expansion film on which the laser isradiated.

The first substrate may include a pixel area in which at least one OELD(organic electroluminescent device) including a first electrode, anorganic layer, and a second electrode is formed and a non-pixel areawhich is formed outside the pixel area. The second substrate may bebonded to an area of the first substrate including the pixel area. Thefrit may be coated on an area of the non-pixel area between the firstand second substrates.

Another aspect is a method of manufacturing an organic light-emittingdisplay (OLED) apparatus using a frit sealing system bonding first andsecond substrates to each other using a frit, including: coating andmelting the frit on one of the first and second substrates; disposingthe second substrate on the first substrate; sequentially disposing athermal expansion film and a mask on the second substrate; and radiatinga laser on the second substrate to harden the frit and expand thethermal expansion film in order to pressurize the second substrate.

An area of the thermal expansion film on which the laser is radiated mayexpand locally.

The radiation of the laser on the second substrate may include: leadinga portion of the laser radiated toward the second substrate to melt thefrit; and leading an other portion of the laser to expand the thermalexpansion film around the frit.

The mask may include a base formed of a transparent material and a metallayer formed on a surface of the base. The leading of the other portionof the laser to expand the thermal expansion film may include leadingthe other portion of the laser to heat the metal layer of the mask andleading the heated metal layer to expand the thermal expansion film.

The radiation of the laser on the second substrate may further includepressurizing the mask to keep a fixed position of the mask when thethermal expansion film expands.

Another aspect is a frit sealing system for bonding first and secondsubstrates to each other using a frit, comprising: a thermal expansionfilm formed on the second substrate to pressurize the second substratewhen heat is applied to the frit and thermal expansion film, wherein thefrit is interposed between the first and second substrates; and a maskformed on the thermal expansion film.

In the above system, at least part of an area of the thermal expansionfilm to which the heat is applied expands. In the above system, aplurality of openings are formed in the thermal expansion film, andwherein the openings are formed substantially directly above the frit.The above system further comprises a laser radiator configured to applya laser beam to the frit through the mask, the thermal expansion filmand the second substrate. In the above system, the mask comprises i) abase which is formed of a transparent material and ii) a metal layerwhich is formed on a surface of the base. In the above system, aplurality of openings are formed in the metal layer along a movementpath of the laser radiator. In the above system, the laser radiator isconfigured to melt the frit and expand an area of the thermal expansionfilm around the frit.

In the above system, the laser radiator is configured to heat the metallayer of the mask, and wherein the heated metal layer is configured toexpand the thermal expansion film. In the above system, the laserradiator is configured to move along a trajectory corresponding to aclosed curve and radiate the laser on the frit which is formed on asurface of the first substrate in the closed curve, in order to heat thefrit and expand an area of the thermal expansion film on which the laseris radiated. In the above system, the thermal expansion film is formedof at least one of polymer and elastomer having relatively high thermalexpansion coefficients. The above system further comprises a pressurizerconfigured to pressurize the mask in order to prevent the mask frommoving when the thermal expansion film expands.

In the above system, the first substrate comprises i) a pixel area andii) a non-pixel area which is formed outside the pixel area, wherein thepixel area comprises at least one organic electroluminescent devicewhich includes a first electrode, an organic layer, and a secondelectrode is formed, wherein the second substrate is bonded to an areaof the first substrate comprising the pixel area, and wherein the fritis formed on the non-pixel area between the first and second substrates.

Another aspect is a method of manufacturing an organic light emittingdisplay apparatus using a frit sealing system bonding first and secondsubstrates to each other using a frit, comprising: forming the frit onone of the first and second substrates; forming the second substrate onthe first substrate; forming a thermal expansion film on the secondsubstrate; and forming a mask on the thermal expansion film; applyingheat to the second substrate and the thermal expansion film to hardenthe frit so that at least part of the thermal expansion film expands bythe heat and pressurizes the second substrate.

In the above method, the second substrate is heated by radiation of alaser. In the above method, the radiation of the laser on the secondsubstrate and the thermal expansion film comprises: first radiating aportion of the laser toward the second substrate to melt the frit; andsecond radiating another portion of the laser to expand the thermalexpansion film around the frit. In the above method, the mask comprisesa base formed of a transparent material and a metal layer formed on asurface of the base, and wherein the second radiating comprises heatingthe metal layer of the mask so that the heated metal layer expands thethermal expansion film. The above method further comprises pressurizingthe mask to prevent the mask from moving when the thermal expansion filmexpands.

Another aspect is a frit sealing system for bonding first and secondsubstrates to each other using a frit interposed between the substrates,the system comprising: a thermal expansion layer formed on the secondsubstrate and configured to expand so as to pressurize the secondsubstrate when heat is applied to the thermal expansion layer, thesecond substrate and the frit.

The above system further comprises a mask formed on the thermalexpansion layer, wherein the mask is configured to receive and transferthe heat to the thermal expansion layer. In the above system, aplurality of openings are formed in the thermal expansion layer andwherein the openings are formed substantially directly above the frit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a frit sealing systemaccording to an embodiment of the present invention.

FIG. 2 is a plan view of the frit sealing system of FIG. 1.

FIG. 3 is a cross-sectional view of the frit sealing system of FIG. 1.

FIG. 4 is a schematic cross-sectional view of an organic light-emittingdisplay (OLED) apparatus according to an embodiment of the presentinvention.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

Generally, an OLED apparatus includes a pair of electrodes, i.e., firstand second electrodes, and at least one organic layer interposed betweenthe two electrodes. The first electrode is formed on a first substrateand operates as an anode that injects holes, and the organic layers areformed on the first substrate. The second electrode is formed on theorganic layers to be opposite to the first electrode and operates as acathode that injects electrons.

If moisture or oxygen flows from the surrounding environment into theOLED electrodes are oxidized and peel, thereby reducing the lifespan ofthe OLED, lowering luminous efficiency, and changing light-emittingcolors.

Accordingly, when the OLED is manufactured, sealing is generallyperformed to isolate the OLED from the environment and to preventpermeation of moisture into the OLED. In such a sealing method, organicpolymer such as polyester (PET) or the like is laminated on a secondelectrode of the OLED, alternatively a cover or a cap is formed of ametal or glass including an absorbent. Then, the OLED is filled with anitride gas, and an edge of the cover or cap is encapsulated using asealing material such as epoxy.

However, this sealing method does not completely or substantiallycompletely block undesirable materials such as moisture, oxygen, and thelike that are permeated from the outside. The sealing method is notapplied to an active top-emission OLED vulnerable to moisture, and aprocess of realizing the active top-emission OLED is complicated. Inorder to solve these problems, a capsule sealing method has beenintroduced to improve an adhesive strength between a device substrateand a cap using a frit as a sealing material.

The frit is coated on a glass substrate in order to completely seal agap between the substrate and the cap, thereby further effectivelyprotecting the OLED.

In the capsule sealing method using the frit, frit is coated on sealingparts of OLED, and a laser radiator moves to radiate a laser on thesealing parts of the OLED in order to harden the frit and seal the OLEDapparatuses.

However, if only a laser is used to harden a frit in order to seal OLED,a short-term peeling problem and a long-term reliability problem occur.In more detail, a laser is radiated to melt a frit in order to locallyapply heat without affecting the surroundings. Thus, since a temperaturerises and then instantly drops, micro-cracks are formed in a brittlefrit and frequently progress to peeling. Also, after the sealing processis performed, the micro-cracks coalesce and frequently progress topeeling in a long-term reliability test process.

Embodiments of the present invention will now be described in detailwith reference to the attached drawings.

FIG. 1 is a schematic perspective view of a frit sealing systemaccording to an embodiment of the present invention. FIG. 2 is a planview of the frit sealing system of FIG. 1, and FIG. 3 is across-sectional view of the frit sealing system of FIG. 1.

A frit generally indicates powdered glass, but a frit used inembodiments of the present invention refers to gel glass in which anorganic material is added into powdered glass or solid glass hardened bya laser.

Referring to FIGS. 1 through 3, the frit sealing system includes a bed110, a laser radiator 120, a thermal expansion film (or thermalexpansion layer) 130, and a mask 140.

First and second substrates 101 and 102 are disposed sequentially on thebed 110. A frit 103 is coated or formed between the first and secondsubstrates 101 and 102.

The laser radiator 120 radiates a laser to the frit 103 coated betweenthe first and second substrates 101 and 102 to melt the frit 103 to bondthe first and second substrates 101 and 102 with the melted frit 103.Here, a laser head 121 is supported by a laser head guide 122 andinstalled to move above the first and second substrates 101 and 102. Aheat or energy source other than a laser radiator 120 may be used toapply heat to at least one of the second substrate 102, the frit 103,the thermal expansion film 130 and the mask 140. For the convenience,the laser radiator 120 will be described.

The thermal expansion film 130 is disposed on the first and secondsubstrates 101 and 102 on which the laser is radiated and which arebonded to each other. In one embodiment, only an area of the thermalexpansion film 130 on which the laser is radiated expands in order tolocally pressurize parts of the first and second substrates 101 and 102around the bonded parts of the first and second substrates 101 and 102.The thermal expansion film 130 prevents the mask 140 from directlycontacting the second substrate 102 in order to prevent the secondsubstrate 102 from breaking and being damaged. The thermal expansionfilm 130 will be described in more detail later.

The mask 140 is disposed on the thermal expansion film 130 tosubstantially completely pressurize the first and second substrates 101and 102. In one embodiment, the mask 140 is formed of a transparentmaterial such as a glass material or the like. The transparent mask 140allows the laser to transmit therethrough. Here, the mask 140 includes abase 141, which may be formed of a transparent material such as glass orthe like, and a metal layer 142, which covers at least a portion of thebase 141.

In one embodiment, the metal layer 142 is formed of a metal such ascopper (Cu), aluminum (Al), or the like having high thermal conductivityon a lower surface of the base 141. In one embodiment, the metal layer142 is not formed on a part on which the frit 103 is formed, i.e., on amovement path of the laser, so that the laser reaches the frit 103. Inone embodiment, the metal layer 142 is deposited to a thickness of about1.5 μm or more to prevent the metal layer 142 from being thermalized orwarping due to the increase in temperature when the laser is blocked.

Referring to FIG. 2, the frit sealing system substantiallysimultaneously and/or sequentially bonds the first and second substrates101 and 102 in one or more rows and one or more columns. In oneembodiment, one mother substrate is bonded one time and cut into aplurality of organic light-emitting display (OLED) apparatuses

Referring to FIG. 2, substrates in 4 rows “r1,” “r2,” “r3,” and “r4” andsubstrates in 6 columns “c1,” “c2,” “c3,” “c4,” “c5,” and “c6” arebonded to one another by the frit sealing system. In one embodiment, thelaser radiator 120 moves along one direction, i.e., direction “x” ofFIG. 2, and radiates the laser on the substrates in the one direction tosequentially bond the substrates to one another. For example, the laserradiator 120 moves along edges of the substrates in the row “r1” and thecolumn “c1” to bond the substrates to one another. In one embodiment,the laser radiator 120 moves along the direction “x” to sequentiallybond the substrates in the row “r1” and the column “c2”, the row “r1”and the column “c3,” the row “r1” and the column “c4”, the row “r1” andthe column “c5,” and the row “r1” and the column “c6” and moves to therow “r2” to sequentially bonds the substrates in the row “r2.”

If the laser radiator 120 includes a plurality of laser heads 121, thelaser radiator 120 may skip the substrates in the direction “x”one-by-one to substantially simultaneously bond the substrates to oneanother. For example, if the laser radiator 120 includes three laserheads, the laser radiator 120 substantially simultaneously bonds thesubstrates in the row “r1” and the column “c1,” the row “r1” and thecolumn “c3,” and the row “r1” and the column “c5” to one another andmoves to the next column section along the direction “x” tosubstantially simultaneously bond the substrates in the row “r1” and thecolumn “c2”, the row “r1” and the column “c4,” and the row “r1” and thecolumn “c6” to one another.

The frit sealing system includes the thermal expansion film 130, whichis formed between the first and second substrates 101 and 102 and themask 140, to expand a local area of the thermal expansion film 130 onwhich the laser is radiated, in order to locally pressurize the partsaround the bonded parts of the first and second substrates 101 and 102.

For example, in a structure for coating a glass substrate to seal anOLED apparatus, a gap between a device substrate and a cap issubstantially completely sealed. Thus, the OLED apparatus is furthereffectively protected. A capsule sealing method using a frit asdescribed above involves coating a frit on sealing parts of OLEDapparatuses and moving a laser radiator to radiate a laser on thesealing parts of the OLED apparatuses in order to harden the frit andseal the OLED apparatuses. However, if only a laser is used to harden afrit and seal OLED apparatuses, a short-term peeling problem and along-term reliability problem occur. In order to solve these problems,various general methods had been studied to mechanically pressurize aside of a substrate. However, in this case, the substrate is damagedwhen being pressurized.

In order to solve this problem, the thermal expansion film 130 is formedbetween the first and second substrates 101 and 102 and the mask 140 toexpand the local area of the thermal expansion film 130 in order topressurize the first and second substrates 101 and 102. As a result, thefrit sealing system improves the adhesive strength of the frit andlong-term reliability of cells.

In one embodiment, the thermal expansion film 130 is formed of amaterial having a relatively high thermal expansion coefficient on thesecond substrate 102.

All kinds of materials have thermal expansion coefficients as their ownconstants. A thermal expansion coefficient indicates how much a materialexpands when a temperature increases by about 1° C. A material having ahigh thermal expansion coefficient expands more than a material having alow thermal expansion coefficient when a temperature increases by about1° C. In general, a thermal expansion coefficient of liquid is higherthan that of solid, and materials such as polymer, elastomer, wood, andthe like have higher thermal expansion coefficients than metals.

In one embodiment, the thermal expansion film 130 meets a fewrequirements. The thermal expansion film 130 has a sufficient heatresistance. Even though laser does not directly contact a thermalexpansion film when sealing, a temperature of at least about 200° C. ormore is applied to fully expand the thermal expansion film 130 in orderto pressurize a substrate. In one embodiment, the thermal expansion film130 is formed of a material which endures a temperature of about 250° C.or more for several seconds. In one embodiment, the material of thethermal expansion film does not include moisture or the like because amaterial which emits moisture when a temperature increases highlybecomes a problem in a sealing process.

The thermal expansion film 130 having a high thermal expansioncoefficient and a high heat resistance as described above is formed onthe second substrate 102. In one embodiment, the thermal expansion film130 is formed of polymer, elastomer, or the like having a high thermalexpansion coefficient.

An area of the thermal expansion film 130 is patterned such that thethermal expansion film 130 is not formed on a part on which the frit 103is coated, i.e., on the movement path of the laser. The thermalexpansion film 130 is patterned such that the thermal expansion film 130is not formed on a radiation path of the laser in FIG. 3, but is notlimited thereto. The thermal expansion film 130 may be formed on thewhole surface of the second substrate 102. In this case, the thermalexpansion film 130 is formed of a transparent material so that a laser“L” reaches the frit 103.

The mask 140 including the base 141 and the metal layer 142 is disposedon the thermal expansion film 130 of which area has been patterned.

When the laser “L” radiated from the laser radiator 120 passes throughthe mask 140, i.e., a portion of the laser “L” passes through an uppersurface of the frit 103, where the portion of the laser “L” is absorbedinto the frit 103 through the base 141 and the metal layer 142 of themask 140 and the thermal expansion film 130. Thus, the portion of thelaser “L” melts the frit 103 to bond the first and second substrates 101and 102 to each other. Thermal energy blocked by the metal layer 142 ofthe mask 140 increases a temperature of the metal layer 142 of the mask140. When the thermal energy is transmitted downward, the temperature ofthe thermal expansion film 130 having the high thermal expansioncoefficient increases. Thus, the thermal expansion film 130 expands,thereby pressurizing the second substrate 102 on which the thermalexpansion film 130 is positioned. In one embodiment, only an area aroundan area of the thermal expansion film 130 on which the laser isradiated, i.e., an area around the frit 103, expands, therebypressurizing the second substrate 102.

Since the thermal expansion film 130 expands upward and downward, thethermal expansion film 130 applies a force in a direction for raisingthe mask 140. In one embodiment, a pressurizer or a pressurizing layer(not shown) is further formed to pressurize the mask 140 downward sothat the thermal expansion film 130 does not raise the mask 140. In oneembodiment, if the pressurizer is formed, the thermal expansion film 130expands only in a direction for pressurizing the second substrate 102downward without raising the mask 140.

Therefore, the frit sealing system, including the thermal expansion film130, considerably improves a bonding quality. In addition, only the areaof the thermal expansion film 130 next to the frit 103 may expand topressurize the second substrate 102 so as to focus a pressure on thebonded part, thereby obtaining a high bonding quality. Moreover, thethermal expansion film 130 is interposed between the second substrate102 and the mask 140 in order to prevent the second substrate 102 frombeing damaged due to direct contact with the mask 140.

FIG. 4 is a schematic cross-sectional view of an OLED apparatus 300manufactured by a frit sealing system according to an embodiment of thepresent invention.

Referring to FIG. 4, a plurality of thin film transistors (TFTs) 320 aredisposed on a substrate 301, and an OLED 330 is formed on the TFTs 320.The OLED 330 includes a pixel electrode 331 which is electricallyconnected to the TFTs 320, a counter (or opposite) electrode 335 whichis disposed above the whole surface of the substrate 301, and anintermediate layer 333 which is interposed between the pixel electrode331 and the counter electrode 335 and has at least one light-emittinglayer.

The TFTs 320 are formed on the substrate 301 and include gate electrodes321, source and drain electrodes 323, semiconductor layers 327, gateinsulating layers 313, and interlayer insulating layers 315. The TFTs320 are not limited to the present embodiment of FIG. 4 and may beorganic TFTs including the semiconductor layers 327 formed of an organicmaterial, silicon TFTs including the semiconductor layers 327 formed ofsilicon, or the like. In one embodiment, a buffer layer 311 is furtherformed of silicon oxide or silicon nitride between the TFTs 320 and thesubstrate 301.

The OLED 330 includes the pixel electrode 331 and the counter electrode335 which are opposite to each other, and the intermediate layer 333which is interposed between the pixel and counter electrodes 331 and335. The intermediate layer 333 includes a plurality of layers includingat least one light-emitting layer. These light-emitting layers will bedescribed in detail later.

In one embodiment, the pixel electrode 331 operates as an anodeelectrode, and the counter electrode 335 operates as a cathodeelectrode. In another embodiment, the pixel electrode 331 operates as acathode electrode, and the counter electrode 335 operates as an anodeelectrode.

In one embodiment, the pixel electrode 331 is a transparent electrode ora reflective electrode. If the pixel electrode 331 is a transparentelectrode, the pixel electrode 331 may be formed of ITO, IZO, ZnO, orIn₂O₃. Otherwise, if the pixel electrode 331 is a reflective electrode,the pixel electrode 331 may include a reflective layer formed of, forexample, Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, or a compound of Ag,Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, and Cr and a layer formed of IT, IZO,ZnO, or In₂O₃ on the reflective layer.

In one embodiment, the counter electrode 335 is also a transparentelectrode or a reflective electrode. If the counter electrode 335 is atransparent electrode, the counter electrode 335 may include i) a layerwhich is formed of, for example, Li, Ca, LiF/Ca, LiF/Al, Al, Mg, or acompound of Li, Ca, LiF/Ca, LiF/Al, Al, and Mg to face the intermediatelayer 333 between the pixel and the counter electrodes 331 and 335, andii) an auxiliary electrode or a bus electrode line which is formed of atransparent electrode material such as ITO, IZO, ZnO, or In₂O₃ on thelayer. Otherwise, if the counter electrode 335 is a reflectiveelectrode, the counter electrode 335 is formed of Li, Ca, LiF/Ca,LiF/Al, Al, Mg, or a compound of Li, Ca, LiF/Ca, LiF/AI, AI, and Mg.

In one embodiment, a pixel-defining layer (PDL) 319 covers ends of thepixel electrode 331 and has a thickness that increases toward the edgeof the pixel electrode 331. The PDL 319 defines a light-emitting areaand widens a gap between the end of the pixel electrode 331 and thecounter electrode 335 in order to prevent an electric field fromfocusing on the ends of the pixel electrode 331. Thus, the PDL 319prevents the pixel electrode 331 and the counter electrode 335 fromshort-circuiting.

In one embodiment, one of various types of intermediate layers 333including at least one light-emitting layer is formed between the pixelelectrode 331 and the counter electrode 335. The at least onelight-emitting layer of the intermediate layer 333 may be formed of alow molecular weight organic material or a polymer organic material.

In one embodiment, if the intermediate layer 333 is formed of a lowmolecular weight organic material, i) a hole injection layer (HIL), ii)a hole transport layer (HTL), iii) an emission layer (EML), iv) anelectron transport layer (ETL), v) an electron injection layer (EIL),and the like are stacked in a single or complex structure in order toform the intermediate layer 333. Copper phthalocyanine (CuPc),N,N′-Di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB), andtris-8-hydroxyquinoline aluminum (Alq3) may be used as low molecularweight organic materials. These low molecular weight organic materialsmay be formed using a method such as a vacuum deposition method or thelike using masks.

In one embodiment, if the intermediate layer 333 is formed of thepolymer organic material, the intermediate layer 333 includes an HTL andan EML. Here, the HTL may be formed of poly(3,4-ethylenedioxythiophene)(PEDOT), and the EML may be formed of a polymer organic material such asPoly-Phenylenevinylene (PPV), Polyfluorene, or the like.

The OLED 330 is electrically connected to the TFTs 320. Here, if aplanarizing layer 317 is formed to cover the TFTs 320, the OLED 330 isdisposed on the planarizing layer 317, and the pixel electrode 331 ofthe OLED 330 is electrically connected to the TFTs 320 through contactholes formed in the planarizing layer 317.

The OLED 330 formed on the substrate 301 is sealed by a sealingsubstrate 302. The sealing substrate 302 is formed of one of varioustypes of materials including glass, plastic, and the like.

According to at least one embodiment, in a frit sealing system and amethod of manufacturing an OLED apparatus using the frit sealing system,an adhesive strength of a frit is improved, without damaging thesubstrate. Thus, the long-term reliability of cells is improved.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims.

What is claimed is:
 1. A frit sealing system for bonding first andsecond substrates to each other using a frit, comprising: a thermalexpansion film formed on the second substrate to pressurize the secondsubstrate when heat is applied to the frit and thermal expansion film,wherein the frit is interposed between the first and second substrates;and a mask formed on the thermal expansion film.
 2. The fit sealingsystem of claim 1, wherein at least part of an area of the thermalexpansion film to which the heat is applied expands.
 3. The frit sealingsystem of claim 1, wherein a plurality of openings are formed in thethermal expansion film, and wherein the openings are formedsubstantially directly above the frit.
 4. The frit sealing system ofclaim 1, further comprising a laser radiator configured to apply a laserbeam to the fit through the mask, the thermal expansion film and thesecond substrate.
 5. The frit sealing system of claim 4, wherein themask comprises i) a base which is formed of a transparent material andii) a metal layer which is formed on a surface of the base.
 6. The fritsealing system of claim 5, wherein a plurality of openings are formed inthe metal layer along a movement path of the laser radiator.
 7. The fritsealing system of claim 5, wherein the laser radiator is configured tomelt the fit and expand an area of the thermal expansion film around thefit.
 8. The frit sealing system of claim 7, wherein the laser radiatoris configured to heat the metal layer of the mask, and wherein theheated metal layer is configured to expand the thermal expansion film.9. The frit sealing system of claim 4, wherein the laser radiator isconfigured to move along a trajectory corresponding to a closed curveand radiate the laser on the frit which is formed on a surface of thefirst substrate in the closed curve, in order to heat the frit andexpand an area of the thermal expansion film on which the laser isradiated.
 10. The frit sealing system of claim 1, wherein the thermalexpansion film is formed of at least one of polymer and elastomer havingrelatively high thermal expansion coefficients.
 11. The frit sealingsystem of claim 1, further comprising a pressurizer configured topressurize the mask in order to prevent the mask from moving when thethermal expansion film expands.
 12. The frit sealing system of claim 1,wherein the first substrate comprises i) a pixel area and ii) anon-pixel area which is formed outside the pixel area, wherein the pixelarea comprises at least one organic electroluminescent device whichincludes a first electrode, an organic layer, and a second electrode isformed, wherein the second substrate is bonded to an area of the firstsubstrate comprising the pixel area, and wherein the frit is formed onthe non-pixel area between the first and second substrates.
 13. A fritsealing system for bonding first and second substrates to each otherusing a frit interposed between the substrates, the system comprising: athermal expansion layer formed on the second substrate and configured toexpand so as to pressurize the second substrate when heat is applied tothe thermal expansion layer, the second substrate and the frit.
 14. Thefrit sealing system of claim 13, further comprising a mask formed on thethermal expansion layer, wherein the mask is configured to receive andtransfer the heat to the thermal expansion layer.
 15. The frit sealingsystem of claim 13, wherein a plurality of openings are formed in thethermal expansion layer and wherein the openings are formedsubstantially directly above the frit.